The present invention relates to a fluid friction clutch comprising a rotatable assembly having a working chamber connected with a working fluid reservoir, the presence of working fluid in said working chamber serving to transfer torque between said rotatable assembly and a rotatable disc disposed in said working chamber. More particularly, the present invention relates to a fluid friction clutch with valve means for controlling the admission of working fluid to said working chamber from a working fluid reservoir and with pressure-responsive means for actuating said valve means.
A fluid friction clutch of the foregoing general type is disclosed in U.S. Pat. No. 4,176,630 (see FIGS. 5 and 6). This known fluid friction clutch has the disadvantage that the actuator mechanism requires two bearings, i.e. a radial bearing and an axial bearing, and a tappet or push rod. As a result of this structure, the fluid friction clutch assembly is more massive than is desirable, and the clutch assembly is also relatively expensive.